Protractor



J. NEUMAIER. PROTRACTOR. APPLICATION FILED JUNE 6. 1919.

Patented Aug. 9, 1921.

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center 7. This plate Co JOHN NEU'MAIER, 0F DAYTON, OHIO.

PROTRAGTOR.

. Specification of Letters Patent.

Patented Au 9, 1921.

Applicaiton filed June 6, 1919. Serial No. 302,315. 1

T 0 all whom it may concern:

Be it known that I, JOHN 'NEUMAIER, a citizen of the United States, residing at Dayton, in the county oi Montgomery and State of Ohio, have invented certain, new and useful Improvements in Protractors, of which the following is a specification.

The object of this invention is to provide a new and improved form of protractor for use. in a drafting room or a machine shop.

Another object or this invention. is to provide the pr'otractor with an extension straight, edge th enlarge the range of use of the. protractor.

These and other objects of the: invention will be fully shown in the drawings, de scribed in the specification and pointed out in the claims at the endthereof.

In the drawings,

Figure 1 is a plan View of the protractor embodying my invention.

Fig. 2 is: a detail viQW of g- 'i a s c i on, b Figs. 1 and 2.

ge a e t on on h l ne Fig. 1.

In the several figures of the drawings, hke reference numerals indicate like parts.

The invention ofthis application is an improvement on the. inyentlon shown in my p ior application No, 9, 25, F 2 1 i In the drawings, reference numeral 1 1ndicates one arm of theprotractor and 2 and 3 indicate the, other arms of the protractor, the arm 1 extending from one side of. the center and the, arms 2 and 3 extending from the other side of the center, all three of the arms swinging on the same center. Integral with the plate 1 is the d1a1 plate 4, which dial of holes 5, 5, therein, which holes are spaced equal number of degrees apart between centers, the unit of measurement preferably used being 10.

Mounted the extension.

line 33-3 of ha the. plate 4 is t p a 6 adapted to swing independently around the at 8 w i h is concen ric with. a se of holes 5, 5 on the plate 4.. A in 9 is provicled which en ages w th the hole 8 end with one of the holes 5 so that by Shlfilring the pla e 6 M g the plate 4;, the tWo;pla cs.ca .1 2c- 10ck t0- gsthr y h P n. 9. i th t ros t on- R idly ast ned. to. t e i he plat 10! is p ate. vcr ap jth B1??? 6 id s at is adjustable and that will late s provided with a series ntains one large hole,

o anyd sired' po tio intended to swing over the edge of it. 'In the plate 10 is provided a series of ten holes, which holes are concentric with the center 7 and are spaced certain distances apart. In the plate 6 is also provided a series of holes, which holes are also concentric with. the center 7 and are spaced one degree farther apart between centers than are the holes in the series in the plate 10. The series of holes in the plate lOand in the plate 6 are placed at the same distance from the. center 7. An arm 11 is provided having a pin 12 thereon, which pin is concentric with both series of holes in the plates 6 and 10. The pin can pass through one hole of each series and normally passes through the'O hole of both series inplates 6 and 10. WVhen the pin is disengaged from the plates 6 and 10 the arm 2 may be shifted so asto move the first hole on the plate 10into position over the first hole on the plate 6, and the pin can then engage with these two holes tolock these two plates together, in which position the arm 2 will be advanced 1 beyond the position which it occupied when the pin engaged the 0 holes of both plates. In like manner, the plate 10 may be advanced an other step or steps so that the pin 12 will engage with any other pair ofholes bearing the same number in the. two'plates and shoulder 15 on the arm 2 and bears against an anti-friction roller mounted on a pin 16 on the arm 3. The plate 14 is wedge shaped and has a scale thereon which is divided into sixtyspac'es of equal length,

Pl s lf' ia ng t sses on arm 3 1 each of which spaces represent one minute. .TheO mark.

19 thereon which engages with the dovetailed groove 17. This plate projects over the arm 3 and supports an extension plate or straight edge 20 in the following manner.

The extension 20 has a clove-tailed groove 21 therein which is engaged by tongues 22, 31 and 32 below the plate 18. The tongue 22 is loose and is supported by a pin 23 and thumb nut 24. A washer 25 is interposed between the thumb nut 24 and the plate 18. By screwing down on the thumb nut 24, the pin 23 and tongue 22 are drawn up, the tongue raising the plate 20 against the plate 18 and holding it firmly in place thereunder. The thumb nut 24 can be loosened which will in turn loosen the tongue 22 and per- Init the plate 20 to slide thereon to any desired position in which it may then be clamped by tightening up on the thumb nut 24. The tongues 31 and 32 are rigid with the plate 18.

The arm 1 is grooved in the same manner and the plates 18 and 20 may be removed from the arm 3 and engaged with the arm 1 in the same manner as above described.

The arm 3 is provided with a set screw 26 and the arm 1 is provided with the set screw 27 The plate 18 is recessed at 28 and 29 so as to make slotted engagement with the screw and will be clamped in place thereby, it being understood that the plate 18 is in proper position when it bears against the set screw.

It will be understood that this protractor will be used without the extension for measuring ordinary angles formed at one side of their common pivot center with the sides of one of the arms. The extension will be used for measuring the complement of the angle formed on the other side of their common pivot center. If the arm 1 is used as the base and the extension is applied to the arm 3, the extension 20 will measure the same angle measured by the arm 3. If the extension is applied to the arm 1 and the arm 3 is used as a base the same result will be secured but the position of the instrument can thereby be reversed and readings taken therefrom with the same facility in either case.

I claim:

1. A protractor having two arms thereon pivoted on a center and extending normally in the same direction therefrom, the outside of each arm being parallel to the outside of the other arm when in zero position, one of said arms having its inner edge extending radially from the center and the other arm having its inner edge normally parallel to and spaced apart therefrom with an open space between them, an extension on one of said arms extending in the opposite direction, said arms being adapted to measure angles on one side of the common pivot: of the arms, the extension being used to measure the same angle at the other side of the pivot of the arms, the extension being used to measure the same angle at the other side of the common pivot of the arms, said extension being applicable to either arm, the arm carrying the extension being used as the side and the other arm being used as the base of the protractor.

3. A protractor having two arms thereon pivoted on a center and extending normally in the same direction therefrom, an extension on one of said arms extending in the opposite direction, said arms being adapted to measure angles on one side of the common pivot of the arms, the extension being used to measure the same angle at the other side of the common pivot of the arms, said extension being applicable to either arm, the arm carrying the extension being used as the side and the other arm being used as thebase of the protractor, one of said arms having a dovetail groove thereon, a platefhaving a tongue thereon adapted to engage with said groove, means for clamping a section of said tongue in said groove, an extension arm mounted'to slide on said plate in parallel relation to the arm supporting the plate.

4. A protractor having two arms thereon pivoted on a center and extending normally in the same direction therefrom, an exten sion on one of said arms'extending inthe opposite direction, said arms being adapted to measure angles on one side of the common pivot of the arms, the extension being used to measurethesame angle at the other side of the common pivot of the arms, said extension being applicable to either arm, the arm carrying the extension being used as the side and the other arm being used as the base of the protractor, each of said arms having a dovetail groove therein, a. plate having a tongue thereon adapted to engage'with the groove in either arm, meansfor clamping a section of said tongue in said groove, an extension arm mounted to slide on said plate in parallel relation to the arm supporting the plate, said protractor being made reversible by transferring the plate and extension from one arm tothe other.-

I 5. A protractor having two arms thereon pivoted on a center and extending normally in the same direction therefrom, an extension on one of said arms extending in the opposite direction, said arms being adapted to measure angles on one side of the common pivot of the arms, the extension being used to measure, the same angle at the other side of the common pivot of the arms, said extension being applicable to either arm, the arm carrying the extension being used as the side and the other arm being used as the base of the protractor, one ofsaid arms having a blind dovetail groove therein, a binding screw located at the end of saidgroove, a plate having a tongue thereon adapted to engage with said groove, said plate having a forked end adapted to engage under the head of said screw to be clamped in place thereby.

6. A protractor having two arms thereon pivoted on a center and extending normally in the same direction therefrom, an extension on one of said arms extending in the opposite direction, said arms being adapted to measure angles on one side of the common pivot of the arms, the extension being used carrying the extension being used as the side and the other arm being used as the base of the protractor, one of said arms having a blind dovetail groove therein, a binding screw located at the end of said groove, a plate having a tongue thereon adapted to engage with said groove, said plate having a forked end adapted to engage under the head of said screw to be clamped in place thereby, an extension arm mounted to slide on said plate in parallel relation to the arm supporting the plate.

In testimony whereof I afiix my signature.

JOHN NEUMAIER. 

